user-set pie chart

Hi everyone,

Just wondering if anyone knows a straightforward way to allow a use to input values into a number of categories and have a pie chart responsively display their choices, ultimately revealing a layer with the correct distribution on the pie chart.

I think I can handle setting up the second part with the layer. But, any idea for the interactive pie chart? E.g. I provide them 3 categories of high-medium-low, and they set the ratios as 1/3-1/3-1/3 and the pie chart shows that division. Then I reveal that it's actually 1/4-1/4-1/2. I'm looking into using the interactive dials, but they're sub-optimal for this task.

Thanks